Oxygen-Containing Radicals and Hydrogen Peroxide Delignification

The oxygen-containing radicals, including hydroxyl radicals, superoxide anion radicals and hydroperoxyl radicals, in peroxide bleaching and the relationship between the radicals and hydrogen peroxide delignification are introduced. The way of the radicals producing, the radicals reaction with lignin, the delignification selectivity of hydroxyl radicals and the pH effect on the selectivity are discussed. It is con- sidered that the transfer of hydrogen peroxide, the producing and concentration of the radicals can be controlled by controlling the pressure, temperature and hydrogen peroxide charge in the bleaching system. The delignification ability of hydrogen peroxide can be strengthened and the bleaching results can be improved with the aid of radicals reaction.